Hi there!
It's best to ask this question on the DVC board. Not a lot of people who hang around this board are DVC members. But as far as I know, it's usually not worth it and keep your points for the US destinations.
For how long to go is really about what you want to achieve and how much of a hardcore Disney fan you are. And do you think you will ever go back?
What is possible, keeping in mind that, unless you go in the first week of June, high season has started, but the parks are open till late.
1 day: All the highlights in both parks, with good use of FP. (Look into the paid fastpass options)
2 days: All the highlights, plus some shows and the smaller rides.
3 days: Do it 'all', the shows, the smaller rides and repeats.
4 days: Really take your time, stop and smell the roses, sleep in a day, etc.
Start here with your reading:
https://www.disboards.com/threads/faq-1st-time-visitors-crowds-weather-language-wifi-money.3736354/
And to answer your question in the other thread. When you go the
Disneyland Paris website, in the top right corner you can switch the country & language. It is encouraged to check the other countries as they all have different offers for hotel & ticket packages. The US website usually gives the worst prices (probably because DLP knows Americans do not know to check the other countries ). Due to EU regulations, you are allowed, without any problem, to book an offer from the German website, while you are from the US.
Compare all the different packages, some include a discount on the room, others offer a free dining plan etc.
When you book directly through Disney, it is not possible to get less park days then you have booked nights. If, for example, you want to stay 5 nights and only 2 day park tickets, you cannot book that directly via Disney. If you book 5 nights, you will get 6 day park tickets, including your arrival and departure day.
If you would want to do it like this, book your hotel via sites like Expedia.com, booking.com, hotels.com, trivago.com, and book your tickets via the Disney website. But do the math first, especially because the Disney packages can include free dining.
There is some discussion about Newport Bay, it got some less favourable reviews recently, so probably skip this hotel. I'll check it out in a few weeks, so curious to see
When thinking about staying onsite at Disneyland Paris, keep in mind that it's a hotel, not a resort. There are less amenities on site. The majority of the guests just uses the hotel to sleep, not to really spend hours in. Resort hopping is not a thing here, also our Disney Springs (called Disney Village) is much smaller, so no need to dedicate much time to explore resorts or hours of shopping in Disney Village.
Let go of your inner planner, you do not need your inner planner here. You cannot pre-book your fastpasses etc. Just have a basic plan of what you want to achieve, book table service restaurant if you want 3 months in advance (keep your expectations of the food low, it's not a dining destination like WDW, for good French food go to Paris or the country).
The main thing for American visitors to keep in mind, especially if they are in love with WDW, is to keep an open mind and don't expect everything to be the same as in the US. You can have an amazing time in Disneyland Paris
but with adjusted expectations.